Microdialysis Analyzer and Flame Atomic Absorption Spectrometry in the Determination of Blood Glucose, Lactate and Magnesium in Gerbils Subjected to Cerebral Ischemia/Reperfusion

Abstract

Objective: Flame atomic absorption spectrometry (FAAS) and a microdialysis analyzer were employed for dynamic monitoring of magnesium (Mg), glucose and lactate levels in blood samples of gerbils subjected to cerebral ischemia.

Methods: Focal cerebral ischemia was induced by occlusion of the unilateral common carotid artery and the middle cerebral artery for 60 minutes followed by 180 minutes of reperfusion. Whole blood samples were continuously collected from the jugular vein via an auto-blood sampling system. The dynamic profiles of Mg, glucose and lactate before, during and after ischemia were determined.

Results: During cerebral ischemia, blood Mg levels gradually rose to 130% of the baseline and returned to the basal levels within 30 minutes after reperfusion. Lactate concentrations decreased to approximately 50% of the basal levels during cerebral ischemia and returned to basal levels immediately after reperfusion. Glucose levels remained the same during cerebral ischemia and gradually fell to 50% of basal levels at the end of reperfusion. The linearity ranges of glucose, lactate and Mg were 0.1–25 mM, 0.02–2.5 mM and 5–1500 μg/L, respectively. The required volume of each blood sample is less than 30 μL. The intra- and inter-assay variation was less than 3%. Since blood loss is minimal from repeated blood sampling, it is suitable for small animals.

Conclusions: Mg may be accumulated in blood cells, which are helpful for reducing glucose utilization. As a result, less lactate was produced during the acute phase of cerebral ischemia. Preservation of glucose is advantageous for brain cells’ restoration after ischemia.

• cerebral ischemia
• magnesium
• energy metabolites
• microdialysis
• graphite furnace atomic absorption spectrometry

This study was supported by grants from Taichung Veterans General Hospital (TCVGH-917306C & 917311D) and the National Science Council (NSC-91-2113M-075A-002), Taiwan, the Republic of China.